Rows to single cell - sql

Question

I would like to get the desired output marked in green
the data points for each id get put into a single cell
Basically take all the events that have happened with A and attach it in the same order

Answer 1

Use Stuff Function:
DECLARE #tblTest AS Table(
ID INT,
EVENT VARCHAR(5)
)
INSERT INTO #tblTest VALUES
(1,'A'),
(1,'A'),
(1,'C'),
(2,'A'),
(2,'B'),
(2,'C')
SELECT DISTINCT
T1.ID,
STUFF
(
(SELECT '' + convert(varchar(10), T2.EVENT, 120)
FROM #tblTest T2
where T1.ID = T2.ID
FOR XML PATH (''))
, 1, 0, '') AS EVENT
FROM #tblTest T1

Answer 2

You can use FOR XML:
SELECT DISTINCT
ID,
(SELECT [EVENT] +''
FROM YourTable
WHERE ID = y.ID
FOR XML PATH('')
) as [EVENT]
FROM YourTable y
Output:
ID EVENT
1 AABCD
2 AABBCC

Answer 3

You can use UDF to do so as follows:
CREATE TABLE t(
id INT,
col CHAR(1)
);
INSERT INTO t VALUES (1,'a');
INSERT INTO t VALUES (1,'b');
INSERT INTO t VALUES (1,'c');
INSERT INTO t VALUES (1,'d');
INSERT INTO t VALUES (2,'e');
INSERT INTO t VALUES (2,'f');
INSERT INTO t VALUES (3,'g');
INSERT INTO t VALUES (4,'h');
The UDF (User defined function) -
USE [t]
GO
CREATE FUNCTION dbo.ConcatenateCols(#Id INT)
RETURNS VARCHAR(MAX)
AS
BEGIN
DECLARE #RtnStr VARCHAR(MAX)
SELECT #RtnStr = COALESCE(#RtnStr + '','') + col
FROM dbo.t
WHERE id = #Id AND col > ''
RETURN #RtnStr
END
GO
Finally the query and result:
SELECT id, dbo.ConcatenateCols(id) AS Cols -- UDF - ConcatenateCols(id)
FROM t GROUP BY Id

Answer 4

CREATE TABLE #temp(Id INt,Event Nvarchar(25))
INSERT INTO #temp
SELECT 1,
'A'
UNION ALL
SELECT 1,
'A'
UNION ALL
SELECT 1,
'B'
UNION ALL
SELECT 1,
'C'
UNION ALL
SELECT 1,
'D'
UNION ALL
SELECT 2,
'A'
UNION ALL
SELECT 2,
'A'
UNION ALL
SELECT 2,
'B'
UNION ALL
SELECT 2,
'B'
UNION ALL
SELECT 2,
'C'
UNION ALL
SELECT 2,
'C'
SELECT DISTINCT ID,
(SELECT [EVENT] +''
FROM #temp
WHERE ID = y.ID
FOR XML PATH('') ) AS [EVENT]
FROM #temp y